是的，children playing 是动名词的复合结构，或者叫含有逻辑主语的动名词短语。该结构可以做主语，还可以用在及物动词或介词之后作宾语，请看例句：

Mary’s crying annoyed him. 玛丽的啼哭让他恼火。

She didn’t mind his (him) asking questions. 她不介意他问问题。

Can you hear the noise of the sofa being dragged? 你能听见沙发被拖动的声音吗？

Have you heard of women playing football? 你听说过女的踢足球吗？

The novel is about three sisters growing up. 这部小说讲述了姐妹三人的成长历程。

I heard a strange sound, like a railway train passing my window. 我听到一阵奇怪的声音，就好像一列火车在我的窗外行驶一样。